I have 'export RSYNC_RSH=ssh' in my profile, and use this form all the
time:

rsync -vazP /vservers/0001/ machine-b:/vservers/0001

BTW (for anyone who's interested), I did my first vserver move from
one machine to another the other week, and it went very nicely. To
minimise downtime, I did things like this:

- an rsync before stopping any services to copy the bulk of the data
(this took a while)

- an rsync after stopping httpd, postgresql, cron, etc. and just
leaving the most important authentication/accounting service running
(this took about 10 minutes, mostly due to the postgresql data files
which had changed)

- an rsync after stopping the vserver (this didn't take long at all
since there were only a few logs changed)

- clear the arp cache on the local router

- start vserver on the new box with only the auth/acct service running

- test and check various things

- start the remaining services

The end-user visible downtime was under 5 minutes.

Of course, this was just confirmation of what I knew could be done,
but it was exciting to see it go so smoothly and quickly. Thanks
Jacques!